Modeling Bone mineral density (BMD) evolution in postmenopausal patients treated by letrozole (L), tamoxifen (T) and sequences of T and L (SAKK 21/07)


Serval ID
Inproceedings: an article in a conference proceedings.
Publication sub-type
Poster: Summary – with images – on one page of the results of a researche project. The summaries of the poster must be entered in "Abstract" and not "Poster".
Modeling Bone mineral density (BMD) evolution in postmenopausal patients treated by letrozole (L), tamoxifen (T) and sequences of T and L (SAKK 21/07)
Title of the conference
2009 ASCO Annual Meeting
Zaman K., Thürlimann B., Huober J., Schönenberger A., Pagani O., Lüthi J., Simcock M., Giobbie-Hurder A., Genton C., Aebi S.
Working group(s)
on behalf of the Swiss Group for Clinical Cancer Research (SAKK).
Orlando, Florida, May 29 - June 2, 2009
Publication state
Issued date
Journal of Clinical Oncology
Background: Osteoporosis and fractures are long term complications of aromatase inhibitor use in the adjuvant therapy of breast cancer. Early detection of patients (pts) at risk of treatment-induced osteoporosis may allow preventive therapy and selection of the most appropriate endocrine therapy. We developed a statistical model describing the evolution of BMD in pts treated with T, L and sequences of T and L. Methods: Available dual-energy x-ray absorptiometry exams (DXA) of pts treated in trial BIG 1-98 were retrospectively collected from Swiss centers. Treatment arms: A) T for 5 years; B) L for 5 years; C) 2 years of T followed by 3 years of L; and D) 2 years of L followed by 3 years of T. Pts without DXA were used as a control for detecting selection bias. A repeated measures model using the first-order autoregressive covariance structure to allow for different times between DXA was used to model BMD (g/cm2) since trial randomisation. Prospectively defined covariates were considered as fixed effects in a multivariable model using an intention to treat analysis. Covariates at trial randomization were: age, height, weight, race, known osteoporosis, tobacco use, prior bone fracture, prior hormone replacement therapy (HRT), bisphosphonate use and previous neo-/adjuvant chemotherapy (ChT). Results: A total of 247 out of 546 pts had between 1 and 5 DXA; a total of 576 DXA were collected. Arm A contained 67 pts, B 63 pts, C 55 pts and D 62 pts. Median follow-up was 5.8 years. Factors correlated with BMD in the multivariate analysis were weight (0.003/kg, p < 0.0001), height (0.003/cm, p = 0.0083), osteoporosis (-0.130, p < 0.0001), tobacco (current / previously vs. never: -0.057, p = 0.0011 / -0.042, p = 0.0798), previous HRT (0.030, p = 0.0244), ChT (0.032, p = 0.0174), time since endocrine therapy start (-0.009/year, p = 0.0164) and treatment arm (B / C / D vs. A: -0.068, p = 0.0002 / -0.091, p < 0.0001 / -0.064, p = 0.003). Conclusions: Our statistical model describes the BMD evolution for pts treated with L and/or T. All treatment regimens affect BMD. Contrary to expectation, the switch schedule T followed by L does not seem to result in better bone protection compared to L monotherapy
Create date
11/06/2009 11:46
Last modification date
20/08/2019 16:00
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